Nanowerk January 19, 2021 Conventional optical-fiber-based pulsed lasers have limits to increasing the number of pulses per second above the MHz level. Researchers in South Korea inserted an additional resonator containing graphene into a fiber-optic pulsed-laser oscillator that operates in the domain of femtoseconds (10-15 seconds). This increased data transmission and processing speeds significantly. They synthesized graphene, which has the characteristics of absorbing and eliminating weak light and amplifying the intensity by passing only strong light into the resonator. This allows the laser intensity change to be accurately controlled at a high rate, and thus the repetition rate of pulses […]
Tag Archives: S&T South Korea
The changing paradigm of next-generation semiconductor memory development
Nanowerk January 12, 2021 It has been reported that spins are formed inside a nanomagnet if electric current is applied to the nanomagnet. There have been no studies on the physical results of these spins. Researchers in South Korea have established a theoretical system by developing a spin diffusion equation that describes the spin conductance in magnetic materials. They discovered that when the spins formed by electric current is emitted to the outside, only the sign is opposite to that of the spins injected from the outside, and the effects are the same. Therefore, the directions of the N pole […]
Researchers control multiple wavelengths of light from a single source
Phys.org December 10, 2020 In carbon dots multi-wavelength emission can be stimulated under a single excitation source, enabling the simple and robust generation of white light from a single particle. Carbon dots also exhibit a concentration-dependent photoluminescence; however, this has not been fully understood. To understand this phenomenon and fully utilize the capabilities of carbon dots, researchers in South Korea posited and demonstrated that the dual-color-emissiveness is due to the interparticle distances between each carbon dot. They examined how the relative light intensity of the red and blue colors changed when varying the interparticle distances. They found that as the […]
Active camouflage artificial skin in visible-to-infrared range
Phys.org December 2, 2020 Researchers in South Korea have developed a multispectral imperceptible skin that enables human skin to actively blend into the background both in the IR‐visible integrated spectrum only by simple temperature control with active cooling and heating. The thermochromic layer on the outer surface of the device, which produces various colors based on device surface temperature, expands the cloaking range to the visible spectrum and ultimately completes day‐and‐night stealth platform simply by controlling device temperature. In addition, the scalable pixelization of the device allows localized control of each autonomous pixel, enabling the artificial skin surface to adapt […]
Asymmetric optical camouflage: Tunable reflective color accompanied by optical Janus effect
Phys.org October 20, 2020 Going beyond an improved colour gamut, an asymmetric colour contrast, which depends on the viewing direction, and its ability to readily deliver information could create opportunities for a wide range of applications, such as next-generation optical switches, colour displays, and security features in anti-counterfeiting devices. Researchers in South Korea propose a simple Fabry–Perot etalon architecture capable of generating viewing-direction-sensitive colour contrasts and encrypting pre-inscribed information upon immersion in particular solvents. Based on the experimental verification of the theoretical modelling, they have discovered a completely new and exotic optical phenomenon involving a tunable colour switch for viewing-direction-dependent […]
A new species of darkling beetle larvae that degrade plastic
Science Daily July 20, 2020 Researchers in South Korea found that the larvae of a darkling beetle P. davidis indigenous to East Asia, including the Korean peninsula, can consume polystyrene and reduce both its mass and molecular weight. They confirmed that the proportion of Serratia bacillus in the intestinal tract of P. davidis larvae was responsible for six-fold increase in biodegradation. It was found that the gut flora of this larvae consisted of a very simple group of bacterial species unlike the gut flora of other conventional polystyrene-degrading insects. According to the researchers if we replicate the simple gut floral […]
A ‘hole’ lot of sponge! New technique to create super-sponges is a game changer
EurekAlert June 10, 2020 Unlike traditional porous materials, in theory MOFs structure can be controlled through careful selection of the components of the synthesis process. But in practice, this process is challenged by the restricted synthetic conditions and high thermal and chemical sensitivity of MOFs. Researchers in South Korea introduced stable carbon-carbon bonds by converting existing carbon-hydrogen bonds using elevated temperatures and adding “electrophilic organic halides or carbonyl compounds”, allowing simultaneous introduction of the required functional groups as well as the mesoscopic holes. This technique could potentially improve the safety of workers in enclosed, gas-filled environments such as in the […]
Stretchable lithium-ion battery is based on new micro-honeycomb structure
Nanowerk April 29, 2020 In stretchable batteries the electrodes must have a degree of stretchability because the active materials occupy most of the volume, and the separator and packaging should also be stretchable. Researchers in South Korea have developed an all-component stretchable lithium-ion battery by leveraging the structural stretchability of re-entrant micro-honeycomb graphene–carbon nanotube (CNT)/active material composite electrodes and a physically cross-linked gel electrolyte, without using an inactive elastomeric substrate or matrix. Active materials interconnected via the entangled CNT and graphene sheets provided a mechanically stable porous network framework consisting solely of binder-free, highly conductive materials which provided superior electron […]
Team develops foldable and washable luminescent film
Phys.org April 8, 2020 The conversion of invisible infrared or ultraviolet light into visible light allows us to intuitively see the data contained in the light, and thus enables the use of infrared or ultraviolet light for displays or imaging devices. As ultraviolet light is high in energy its conversion into visible light relatively easy and efficient. A team of researchers in South Korea made a square lattice array of silica microbeads decorated with up-conversion nanoparticles and metal structures. This configuration maximizes both the absorption of near-infrared light and the luminescence of visible light, thus increasing the efficiency of near-infrared-to-visible […]
Making tiny antennas for wearable electronics
Science Daily November 20, 2019 Researchers in South Korea made the antenna by spray-coating several layers of NbSe2 nanosheets onto a plastic substrate. In tests an 885 nm-thick antenna, a 10 × 10 mm patch of the ultrathin material performed well, with a radiation efficiency of 70.6% propagating radio frequency waves in all directions. By changing the length of the antenna, the frequency could be tuned from 2.01 to 2.80 GHz, which includes the frequency required by Bluetooth and Wi-Fi technologies. The antenna could be bent and stretched without large changes in its performance. In addition to wearable electronics, the […]